The present invention relates to a method of manufacturing filter-tipped cigarettes.
In particular, the present invention relates to a method of manufacturing filter-tipped cigarettes using a filter assembly machine and commencing from a dual-rod cigarette manufacturing machine of the type described and claimed, for example, in U.S. Pat. No. 4,418,705, which provides for feeding the filter assembly machine with two continuous cigarette rods traveling axially at substantially constant speed.
On leaving the manufacturing machine, the two continuous cigarette rods are fed through the same cutting head, usually a rotary type, by which they are normally cut into "double portions", i.e. portions twice the length of that which, when joined to the filter, goes to form a normal filter-tipped cigarette. Still traveling axially and pushed from behind by the respective continuous cigarette rods, the double portions are fed to a pickup station where a transfer member simultaneously picks up a pair of double portions, one from each rod, and feeds them inside successive seats on a common roller feeding the filter assembly machine.
As described and illustrated, for example, in U.S. Pat. No. 4,577,644, a filter assembly machine usually comprises a series of parallel feed rollers, each having a number of peripheral seats for receiving a respective double portion and feeding it forward transversely in relation to its longitudinal axis, i.e. perpendicularly to the traveling direction of the double portion as it leaves the manufacturing machine.
Due to the double portions being supplied in pairs to the filter assembly machine along a 90.degree. route, the transfer member, e.g. of the type described in U.S. Pat. No. 4,645,063, must be designed not only to enable a 90.degree. switch in the traveling direction of the double portions, but also to ensure both double portions are fed simultaneously into consecutive seats on the input roller of the filter assembly machine.
Though perfectly efficient, operation of said transfer member, especially as regards simultaneous input of both double portions, is so complex as to be substantially unfeasible at higher than current operating speeds, thus ruling out any possibility of increasing the operating speed of current manufacturing machinery.